The devastating effects of ALS are on full display in “Gleason,” an emotional powerhouse of a documentary charting former NFL star Steve Gleason’s battle with the debilitating disorder. With seemingly no restrictions from his subjects, director Clay Tweel delivers far more than just a typical inspirational living-with-disease doc: This is a portrait of a family forced to completely readjust their lives, never flinching from the accompanying fears and frustrations. Tweel masterfully assembles roughly four years of footage, much of it shot by Gleason himself, and the result is painfully raw at times but undeniably rewarding. His name value should provide a commercial stepping stone for a doc with strong potential to score across all platforms; Amazon purchased U.S. rights at Sundance, and will partner with Open Road on theatrical release.

It would’ve been easy to play Gleason’s story for sentimental uplift meant to inspire others to live life to its fullest, or as a feature-length fundraising ad for the Team Gleason charity assisting those living with ALS. “Gleason” may accomplish both of those things anyway, but any such benefits come honestly and without manipulation by inviting viewers along on an intimate journey and holding nothing back.

Already a modern-day folk hero when he played for the New Orleans Saints, thanks to a pivotal blocked punt during the team’s first game following Hurricane Katrina, Gleason became a symbol of courage in the sports world when he was diagnosed with ALS at the age of 34. The diagnosis was almost immediately followed by the news that his wife, free-spirited artist Michel Varisco Gleason, was pregnant with their first child.

Intent on leaving his offspring something to remember him by before his disease progressed too far (his life expectancy was as little as a few years), Gleason begins taping video journals full of advice, observations and lessons about life, as well as general updates on his own health. A documentary was already under discussion (filmmaker Sean Pamphilon was originally attached to the project), but entrusting anyone with footage so vulnerable and revealing couldn’t have been an easy call.

Especially as the years go on, the disease intensifies and Gleason’s physical condition deteriorates to the point when he can no longer hold his son or take care of his own basic functions (as demonstrated in a frank sequence involving a jolly nurse who arrives to give him an enema). The toll all this takes on Varisco, who is simultaneously trying to raise a toddler, couldn’t be clearer. Seeing two charismatic and adventurous souls reduced to nearly wordless squabbling speaks volumes about living with ALS.

There’s a richly comic streak to the film, too, as Gleason, Varisco and family friend and designated caregiver Blair Casey use humor to offset their situation, and the film makes a viewer feel like a part of what Varisco describes as their “badass unit” — which only makes the story’s more serious elements hit even harder.

Since the project has its origins in the birth of Gleason’s son, Rivers, it’s only appropriate that Tweel (who edited with Brian Palmer) uses the relationship between fathers and sons to shape the narrative. Gleason’s own father, Mike, admits that his son grew up in a “pretty dysfunctional marriage” and his own coping journey — from visiting a faith healer to revealing his greatest challenge is accepting his son might die — is among the film’s most moving threads.

But there are many such threads expertly woven into a piece that earns its place in the pantheon of male weepies several times over. That’s not to say there’s a gender barrier to being touched by Gleason’s struggles, but simply that this is a film grown men of any background will not be ashamed to admit moves them to tears. As if to prove that point, Pearl Jam lead singer Eddie Vedder chokes up on camera when superfan Gleason conducts a pointed interview about Vedder’s nonexistent relationship with his father.

Vedder’s bandmate Mike McCready provides the original song “Hoping and Healing,” which complements several well-chosen tracks including two from Pearl Jam and the Head and the Heart’s “Rivers and Roads.” The overall tech package is solid enough, but the draw here is the sheer volume of footage Gleason made available — so much that extra material carries over throughout the entire end credits.

The study reported that some professional athletes (football, boxing) who have had repeated head injuries and developed what’s called chronic traumatic encephalopathy (CTE) may develop ALS the study was debunked and no evidence was found to support this cause

I don’t understand why traumatic brain injury isn’t mentioned in the article. Is it not addressed in the movie? He had a 7 year career as a Safety. This 2007 study entitled “Head Injury and ALS” shows a definite increase in ALS risk from multiple head injuries. Here’s a direct quote from the abstract: “For participants with multiple head injuries in the past 10 years, the [ALS] risk elevation was more than 11 fold.”